The Dark Days and the Light Month

Abstract

The actual calendars of Indo-European peoples do show intercalary additions to the lunar year but these take the form of intercalary months. Frazer was aware of this, saying that 'there are grounds for thinking that at a very early time the Aryan peoples sought to correct their lunar year, not by inserting twelve supplementary days every year, but by allowing .the annual deficiency to accumulate for several years and then supplying it by a whole intercalary month.' 2 He expressed his puzzlement over this in connection with the Celts of Gaul, commenting: 'Why they abandoned the simple and obvious expedient of annually intercalating twelve days, and adopted instead the more recondite system of intercalating a month of thirty days every two and a half years, is not plain.'3 The answer I have to offer is that the Indo-Europeans never did employ a twelve-day intercalary period but kept the months of the lunar year in line with the natural seasons by inserting intercalary months when required, and that the place of the twelve days in the calendar was not outside the lunar year but inside it. As I see it, the possibility of having a group of twelve days that stand in a functional relationship to the rest of the year arises when the month used in the calendar is not the synodic month of twenty-nine or thirty days but the shorter light month, the period of the moon's visibility. Ten years before Frazer published his remarks, W. H. Roscher had studied the matter of month length in connection with Greek weeks and festivals and had concluded that months of two different lengths-27-8 days and 29-30 days-were known in antiquity, but that the use of the short month of 27-8 days was the older.4 Frazer made no mention of this finding in his discussion of the twelve days, and yet the two ideas of the light month and a set of special days can be seen as complementary and I shall consider them together here. The longest period of the moon's visibility is twenty-eight days and the moon goes through its cycle from new moon, through full moon, to the last crescent of the waning moon in this time. As Plutarch expressed it, referring to the number twenty-eight: 'Such is the number of the moon's illuminations and in so many days does it revolve through its own cycle.'5 Between each pair of light months there is a gap which was called by the Romans the 'interlunium' or 'intermenstruum,' that is, the interval between the moons or the months.6 The treatment of this time of the dark of the moon